RESUMO
Resumen Se considera infección mixta por Mycobacterium tuberculosis (Mtb) a la coexistencia en forma simul tánea y en un mismo paciente de 2 cepas diferentes de Mtb o 2 variantes distintas de la misma cepa. Cuando una de las variantes selecciona mutaciones de resistencia, se denomina heterorresistencia (HTR) monoclonal; en caso de que sean 2 cepas diferentes, una sensible y una resistente (o cepas con diferentes patrones de resistencia), se denomina HTR policlo nal. Se presentan 3 pacientes, HIV/sida, todos con reiterados problemas de adherencia al tratamiento, en los cuales a través de la secuenciación genómica completa de Mtb se diagnosticó HTR monoclonal con coexistencia de 2 variantes de la misma cepa aisladas de muestras de pulmón y ganglios linfáticos, con diferentes perfiles de resistencia en cada uno de los casos. Es importante pensar en la posibilidad de HTR, principalmente en pacientes con múltiples intentos terapéuticos previos y altas poblaciones bacilares, como en el sida avanzado, dado que esta situación compromete potencialmente los resultados del tratamiento al coexistir cepas o variantes de ce pas sensibles y resistentes.
Abstract Mixed infection by Mycobacterium tuberculosis (Mtb) consists in the simultaneous coexistence in the same patient of two different strains of Mtb or 2 different variants of the same strain. When one of the variants selects for resistance mutations, it is called monoclonal heteroresistance (HTR); if there are 2 different strains, one sensitive and one resistant (or with different resis tance patterns), it is called polyclonal HTR. Three cases of HIV/AIDS patients are presented, all with repeated treatment adherence problems, in whom monoclonal HTR was diagnosed through Mtb complete genomic sequentiation with the coexistence of two variants of the same strain isolated from samples from lung and lymph nodes, with different resistance profiles in each case. It is important to consider the possibility of HTR, especially in patients with multiple previous therapeu tic attempts and high bacillary populations, such as in advanced AIDS, since this situation potentially com promises treatment results by coexisting sensitive and resistant variants of a strain (or strains).
RESUMO
Objective To investigate the clinical features and antibiotic susceptibility of osteomyelitis infected by Gram-negative bacteria (G-) in patients suffered from diabetic foot ulcers (DFU). Methods The clinical data of 91 DFU pa-tients accompanied with osteomyelitis (DFO) were retrospective studied. These patients hospitalized in the Tianjin Metabolic Diseases Hospital were divided into two groups, Gram-negative bacteria (G-) group (n=44) and Gram-positive bacteria (G+) group (n=42), respectively. The clinical features were compared between two groups. Logistic regression analysis was used to determine the risk factors for Gram-negative bactreial infection. The Gram-negative antibiogram was summarized. Results A total of 112 pathogens were isolated from 91 patients. G-bacteria were the most frequent pathogens (48.2%), following by G+ bacteria (47.3%) and fungi (4.5%). Pseudomonas aeruginosa was the majority of the G-bacteria. Comparing the two groups, the rate of antibiotic use within the previous 6 months was significantly higher in G-group (75.0%) than that of G+group (52.4%, P<0.05). There were no significant differences in the other indicators between two groups. The Logistic re-gression analysis revealed that the history of antibiotic use was the independent risk factor of G-bacterial infections in DFO patients. Antibiotics susceptibilities reflected G- bacteria were more prevalent to resist to cephalosporins and quinolonem, but sensitive to imipenem, ceftazidine and cefperazone-sulbactam. Conclusion Gram negative bacteria were not only the main pathogens isolated from DFO patients, but also frequently resistant to several popular antibiotics in China. The proper bacteria culture and antibiotic sensitivity test are especially emphasized to patients with DFU.